1. Field of the Invention
This invention relates to valves and in particular to solenoid-operated cartridge valves.
2. Description of the Prior Art
In one form of fluid flow control valve, a poppet is seated against a valve seat to close the valve. The poppet is provided with a through bore which is selectively closed by a pilot valve. The poppet is spring-biased to the closed position with fluid pressure acting on opposite sides of the poppet so as to permit the spring biasing to maintain the poppet closed. When the pilot valve is raised from the valve seat, the fluid pressure behind the poppet is relieved to the through bore, thus permitting the fluid pressure acting upwardly on the poppet to move the poppet from the valve seat and thereby permit flow through the valve.
In one form, the pilot valve is operated by a suitable solenoid having a plunger connected to the pilot valve for selective positioning thereof in effecting the desired fluid flow control.
Such valves are provided in a wide range of sizes depending on the flow capacity desired.
It is further conventional to provide such valves in the form of cartridges, including both the valve and the solenoid operator in a single assembly which, illustratively, may be connected to suitable ports by a threaded adapter portion thereof.
In U.S. Pat. No. 2,951,133 of James E. Davies et al., a hermetically sealed electromagnetic contactor and the like is disclosed wherein a drawn metal member is provided with a central opening through its upper end, which is encircled by an upstanding flange portion extending through an opening in a superjacent cup-shaped housing member.
Arthur J. Foley et al., in U.S. Pat. No. 3,215,902, show a solenoid actuated mechanism wherein the electrical assembly is located between a flux plate and an upper flux plate, with central apertures of the three elements being aligned and mounted upon a cylindrical protruding portion of the core support.
In U.S. Pat. No. 3,446,473, George E. Barker shows a solenoid valve wherein the solenoid housing is threaded to the valve body.
Alfred J. Ludwig, in U.S. Pat. No. 3,593,241, discloses a solenoid valve having a slotted flux sleeve for nesting the winding leads. The magnetic flux path includes a portion established by a pair of magnetizable end members disposed adjacent the opposite end surfaces of the solenoid coil, with a magnetizable center leg defining the end plug.
In U.S. Pat. No. 3,818,398, William J. Barbier et al. disclose an electromagnetic coil assembly wherein a T-shaped tubular shroud formed of ferrous material is press-fitted into each end of the spool supporting the solenoid coil.
In U.S. Pat. No. 4,074,700 of Thomas H. Engle, a valve assembly is disclosed wherein the coil housing provides a flux return path extending toriodally from the coil through an upper portion of a plunger guide, through the plunger, across a working air gap, through a pole piece, through a coil support flange, and up through a coil housing. The coil housing includes an axially extending lip which is sized diametrically to fit closely to the plunger and axially to provide an increased area for flux transfer. The plunger guide is made as thin as practical so that magnetic losses are minimized.